The invention is based on a pressure generator as defined hereinafter. A pressure generator of this type is already known from German Offenlegungsschrift 37 07 068, U.S. Pat. No. 4,805,965; in this pressure generator a rack engages a piston only in a force-locking manner upon a working stroke. To return the piston to its outset position, a helical compression spring is provided, which is disposed coaxially with the piston and thus increases the axial length of the pressure generator structure. The return of the piston is reinforced by a high hydraulic pressure in the brake system. While the return stroke of the piston is limited by a stop, the other end of the accelerated rack meets the piston of a second pressure generator. The drive motor is thus subjected to strong delaying forces.